Method and apparatus for filling containers with explosive slurry

ABSTRACT

Blasting slurries which contain aeration in the form of finely dispersed bubbles of gas are filled into bombs and other containers under pressure, using a fluid force pump and a check valve arrangement, including a special gas vent, to insure complete filling for storage, compensating for shrinkage of the slurry due to cooling. The gas vent is designed to release air or other gas in the container, to facilitate filling, but its outlet openings are closed by check valves or are so fine that slurry cannot escape through them.

Clay

ited States Patent METHOD AND APPARATUS FOR FILLING CONTAINERS WITH EXPLOSIVE SLURRY Robert B. Clay, Bountiful, Utah Interrnountain Research & Engineering Co.,lnc.

Jan. 14, 1970 Inventor:

Assignee:

Filed:

Appl. No.:

US. Cl. ..86/20, 86/1, 141/302 Int. Cl ..F42b 33/02, B67d 3/00 Field of Search ..86/20, 20.3, 20.5, 1; 102/10;

References Cited UNITED STATES PATENTS 7/1958 Stark ..l02/IO 8/1951 De Ranek ..86/1 UX 1 Mar. 7, 1972 3,526,256 9/1970 Jones ..l4l/302X 2,357,245 8/1944 Wetherby-Williams et al....l4l/302 X FOREIGN PATENTS OR APPLICATIONS 1,144,554 2/1963 Germany ..l4l/'3 2 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-.1. J. Devitt Attorney-Edwin M. Thomas ABSTRACT Blasting slurries which contain aeration in the form of finely dispersed bubbles of gas are filled into bombs and other containers under pressure, using a fluid force pump and a check valve arrangement, including a special gas vent, to insure complete filling for storage, compensating for shrinkage of the slurry due to cooling. The gas vent is designed to release air or other gas in the container, to facilitate filling, but its outlet openings are closed by check valves or are so fine that slurry cannot escape through them.

8 Claims, 8 Drawing Figures METHOD AND APPARATUS FOR FILLING CONTAINERS WITH EXPLOSIVE SLURRY BACKGROUND AND PRIOR ART Explosive slurries, such as viscous but pumpable materials, based on liquid solutions of oxidizer salts and containing suspended particulate matter, are sometimes loaded into military bombs and analogous containers using conventional pumping equipment. It is desired to fill such containers completely and have them remain full for shipment in airplanes and other vehicles for several reasons to be mentioned later. Most slurries contain at least a small amount of air or other gas in the form of fine bubbles. Because of such gas inclusion, and because of other physical properties of slurry constituents, the slurry volume changes with temperature changes. Since the slurries usually are warm or hot when loaded, a container filled with aerated slurry by mere gravity flow will not remain full when it cools. As a result, a substantial cavity often develops on the upper side of the storage vessel.

In some cases, of course, formation of such a cavity pocket at the top of the container may not be particularly objectionable. However, in the case mentioned above, i.e., in filling large bombs and other vessels where dynamic stability, e.g., for transport by aircraft, is important, and/or for attaining high bulk density and/or preventing separation of the explosive from the initiating train in detonation, it is highly important to avoid such cavities. Massive movement of mobile material such as slurry inside a partially filled container can be highly objectionable and even dangerous or destructive to the aircraft. Similar objections, though less serious, can arise in transporting tanks in land or water vehicles. The containers may become so unbalanced dynamically as to set up destructive forces. Other difficulties may be encountered in use as well as in handling and transportation of large military bombs or other missiles which are only partly full of mobile or liquid material. Ballistic characteristics may be very seriously affected in the case ofbombs or projectiles.

Aerated slurries of this type usually contain solid particles which may tend to separate by gravity, such as finely ground aluminum, granules or prills of ammonium nitrate, or other oxidizer salts. A thickening agent is used to make the liquid phase viscous and thereby prevent such gravity separation. This increased viscosity tends to hold the microscopic gas inclusions or bubbles against coalescence or separation as well as preventing gravitational segregation of solid particles. The inclusion of such gas bubbles, however, makes these slurries more elastic and more compressible than most liquids. Gas content often is in the range of to percent of the slurry volume. The present invention takes advantage of this compressibility to insure that a filled bomb or other receptacle will remain full, even when storage temperature drops considerably.

SUMMARY Aerated explosive slurries containing solid particles of metal, salt, and other granular, flake or particulate materials, thickened to a viscosity sufficient to prevent physical segregation of the particles by gravity, are filled under pressure into bombs and other containers. The elasticity of the slurry due to aeration makes it possible to overfill" the container. Filling can be accomplished by forcing the slurry into the receptacle through a simple flap-type check valve while allowing air or other gas to escape from the receptacle, enough pressure being applied to compress the gas which is in the slurry per se. For finish filling, an escape port in a container may include small orifices, large enough to permit gas flow but too small for flow of viscous liquid or slurry. Outer screw plug closures may be used outside of or in addition to the flap valves for final sealing of the containers. Finely perforated plastic temporary valves which are expendable may be used as a form of check valve; preferably these are oversealed by solid plugs.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a front elevational view, partly in section and partly diagrammatic, showing the essential elements of a system for filling large vessels with a compressible viscous material such as aerated slurry, according to the present in vention.

FIG. 2 is a top view ofa closure and self-sealing device constituting one aspect of this invention.

FIG. 3 is a sectional view of the apparatus of FIG. 2 taken substantially on the line 3-3, of FIG. 2.

FIG. 4 is a similar sectional view of a modified closure which includes an air release valve.

FIG. 5 is a top view, with parts in section, ofa modified closure including a filler tube connection, and comprising a plug and valve, suitable for filling a receptacle with aerated viscous liquid or slurry under pressure.

FIG. 6 is a fragmentary sectional view of the device of FIG. 5 taken substantially along line 66 of FIG. 5.

FIG. 7 is a plan view ofa further modified inlet valve closure and filler line connection.

FIG. 8 is a transverse sectional view of the structure of FIG. 7, taken substantially along line 8-8 of said Figure.

DESCRIPTION OF PREFERRED EMBODIMENT FIG. I shows in general outline a preferred embodiment of applicants filling system. It comprises a slurry pump 10 adapted to force aerated slurry or other liquid into a bomb ill or other container. The latter is connected to the pump by a hose or conduit line 13. Line 13 is connected in airtight relation through a suitable valve 14, to a filler inlet 15. The hose extends from the outlet of pump 10 which can be of any suitable type for handling slurry and the like. Slurry is brought into the pump from any suitable supply source through an inlet 21.

Because the slurry has air or other gas distributed or entrained in it, in finely divided bubbles, it is somewhat elastic and compressible. Proportions of such gas may range from very small, up to 25 percent or even more by volume at standard atmospheric pressure and temperature. If the receptacle 11 should be filled with slurry not under pressure, some of this entrapped gas may tend to coalesce into larger bubbles, but the viscosity is such that no, or very little, of the entrapped gas actually escapes from the slurry.

By packing such a container as bomb ll completely full of slurry, under pressure of a few pounds per square inch, say 5 to 15 pounds or even a little more, any contraction of the slurry due to cooling is compensated by bubble expansion. This contraction is due partially to pressure reduction in the tiny gas bubbles as calculated by the general gas law PV=nRT. Pressurizing the slurry places each gas bubble under compression so that it tends to expand to compensate for any other reduction in volume due to decreased temperature or a phase change or crystalline change of the slurry product or its ingredients. Aside from this, it is important in explosive slurries to have microscopic gas bubbles for the additional reason that sensitivity of the slurry to detonation is increased by the bubbles. That is, aeration of the slurry makes it easier to detonate, for example at lower temperatures.

In filling a closed container such as vessel 11, the air in the empty container must be permitted to escape. At the highest point of the vessel, an air vent 25 is provided. This vent may take any of several forms; however, it should be designed so that it can be closed, or be self-closing, to prevent escape of slurry after the vessel is full and to retain the pressure. In FIG. 1 a valve 26 serves this purpose.

FIGS. 2 and 3 show a simple arrangement for sealing slurry under pressure in a container. In this case a separate filling opening or connection may be provided for pumping slurry into the vessel 11. The structure shown is for venting air from the vessel. An inner perforate plug 37 is threaded to fit into a threaded opening 36. Plug 37 may be made of expendable material, e.g., molded plastic. It has a polygonal recess or depression 40 adapted to receive a wrench for tightening it tnto place in opening 36. This inner plug is provided with a number of very small openings 42 distributed over its whole bottom area. These openings are preferably too small for appreciable flow of viscous liquid or slurry but are large enough and numerous enough to allow air or other gas to escape quite t'reely from the vessel as it is filled. They are small enough that they will be sealed by the slurry. Plug 37 is strong enough to withstand the maximum pressure exerted by the slurry. When slurry reaches and attempts to flow out of the small openings on completion of a filling operation, they are blocked by it because of its viscosity. Additional slurry may be forced into the container under pressure after the openings 42 are sealed off without any significant amount of it escaping through them. To further insure against leakage, even very slow leakage. the permanent plug 39 can be installed above the pertorated plug in the threaded recess 36. It also has a wrench socket 43.

FIG. 4 shows an alternative system comprising a closure 45 m a threaded opening 47 in vessel 11. This closure is adapted to serve both as a filler connection and a gas control valve. It is provided with a large opening 50, shown as threaded, for a filler tube connection. The filler tube IS not shown. A smaller threaded opening SI is shown into which a perforate screw plug 55 can be screwed. The latter has a longitudinal opening :56 which connects with one or more lateral openings 57 to permit escape of air as the vessel is filled. These openings are small and are exposed to the atmosphere when the plug is partly unscrewed out of closure 45. When the vessel is full, slurry will tend to flow into and at least partly plug the opening .56. The screw plug 55 can be tightened down as soon as the vessel is at a desired pressure to close off the side opening 57. Below opening 50, the plug 45 carries a flap-type check valve 60 attached by a rivet 62. It bends open to admit slurry and swings up to close opening 50 when pumping of slurry into the container 11 is completed. That is, any movement of slurry to llow out closes the flap 60.

Obviously, in order to fill the bomb under pressure, there must always be a filler opening and a check valve or equivalent means must be provided at the tiller opening to prevent backflow of the slurry when the filler tube 18 disconnected or when the pump is stopped or reversed. A preferred arrangement includes a tight connection for a filler tube 70 in the form of a bayonet opening 72, as shown in FIGS. and 6. This connection consists of an externally threaded annular member 74 having intermittent notches 76 and lobes 78 extending radially inward to engage complementary elements 80 on the end of the tube 70. The latter is attached in any suitable manner to a filler hose such as 13, FIG. 1. Annular plug member 74 is adapted to be screwed into a threaded opening 83 in the vessel 11. It comprises a transverse wall element 84 provided with several large openings 85. Hingedly or flexibly attached to member 74 by rivets or the like is flap valve 86. If l'lap 86 has sufficient rigidity. wall 84 may be eliminated. The arrangement is such that as slurry is forced into the vessel through openings 85, the flap 86 swings out of the way, as shown in FIG. 6. When the slurry ceases to flow. the elasticity of member 86 plus a tendency to outward movement of slurry swings it back against the perforate wall 84 and the pressurized slurry inside holds the flap shut. Thereafter, the nozzle 70 may be disconnected by rotating it a partial turn and lifting it out. Sealing by l'lap 86 may be supplemented by inserting a permanent metal plug 111 the threads 83 above the plug member 74, as with member 39, FIG. 3, described above. With moderate pressurizing the container remains full after long storage because the trapped gas bubbles expand or contract to compensate for thermal contraction or expansion.

An alternative filler system is shown in FIGS. 7 and 8. An puter annular plug member 114 is threaded into the opening ll5 is vessel II which also is threaded. Member I14 may be made of an inexpensive expendable plastic material, or it may the of metal. This member. in turn, is threaded internally at M6 to receive ultimately a tight closure plug such as plug 39 of FIG. 2. A threaded bayonet locking element 117 is screwed into member 114 for the filling operation. It is cut out in quadrants as shown at 118 to receive corresponding locking elements I19 of a filler tube 120. The nozzle I20, e.g., at the end of a hose such as 13, FIG. I, is attached in bayonet fashion by inserting its lock elements 119 into the slots or quadrants I18 of member H7 and rotating a partial turn. A fluidtight connection is provided, the arrangement being similar to conventional closures for automobile radiators, gasoline tanks, etc. A stiff closure flap 124 secured to the annular plug member 114 by screws I25 tends to swing shut against the opening 123 in member 114 when the filling operation is completed. Flap I24 is made of a resilient plastic material which may be suitably reinforced by fiber or fabric, etc., if desired. As in the previous example, it closes the container and prevents outflow whenever the slurry tends to flow outward.

As will be obvious to those skilled in the art, various modifications can be made in the method and apparatus within the spirit and purpose of the invention. The invention insures that the bomb, shell, or other receptacle will be filled completely when first loaded and will remain full after extended storage times, even at high temperatures, or in situations where storage temperatures fluctuate widely. For most purposes, a pressure of 5 to 15 pounds per square inch above atmospheric is adequate but higher pressures may be used if desired.

It will be understood that reference above or hereafter to aerated liquid or viscous liquid is intended to cover mobile, flowable or pumpable compositions which may or may not contain suspended particulate matter and which contain trapped air, or other gas, distributed throughout the mass in very fine or microscopic bubbles. Obviously, the material must contain enough of such gas, distributed throughout, that it can be compressed suffieiently to compensate for any shrinkage or volume change that might occur because of temperature changes. The pressure used must be sufficient to compress the slurry or other viscous liquid enough to keep the container full, in spite of any volume changes due to temperature variations.

It will be obvious that variations and modifications in details of apparatus and method may be made without departing from the spirit and purpose of the invention, as will be obvious to those skilled in the art.

What is claimed is:

l. The method of completely filling a container with an aerated flowable mass of gel which contains discrete and compressible gas bubbles so as to prevent subsequent formation of a cavity in said container due to shrinkage of the gel, which comprises, in combination. the steps of venting the air from the container while filling it with said gel and after said filling, further forcing the gel into the container under sufficient pressure to compress said discrete bubbles of gas to compensate for any anticipated shrinkage of the gel, and preventing outflow of said gel from the container during said further forcing.

ll. Method according to claim I which comprises providing In the top of the container outlet openings for said air venting which are large enough for free air flow but small enough to be plugged effectively by said gel when the gel reaches said top.

3. Method according to claim I wherein the liquid is pumped into the container to a positive pressure of 5 to I5 pm.

4. Apparatus for filling completely and pressurizing a contamer with a viscous liquid or gel which contains finely divided but discrete and compressible bubbles of gas in sufficient volume to permit substantial compression of the whole mass of gas-containing gel or liquid, which comprises, in combination, a filler line, means for connecting said filler line in fluidtight relationship to said container, a gas vent in the top of the container adapted to release air from the container as it is filled, a check valve in said filler line to prevent reverse flow of the gas-containing liquid or gel from said container, said gas vent including closure means which are effectively closed by and sealed by the liquid or gel itself when said liquid or gel reaches the top of said container.

viscous liquid to flow therethrough and additional positive closure means to prevent flow of either gas or liquid through said element.

8. Apparatus according to claim 7 which includes a flap valve to prevent backflow of viscous liquid from container to the filler line. 

2. Method according to claim 1 which comprises providing in the top of the container outlet openings for said air venting which are large enough for free air flow but small enough to be plugged effectively by said gel when the gel reaches said top.
 3. Method according to claim 1 wherein the liquid is pumped into the container to a positive pressure of 5 to 15 p.s.i.
 4. Apparatus for filling completely and pressurizing a container with a viscous liquid or gel which contains finely divided but discrete and compressible bubbles of gas in sufficient volume to permit substantial compression of the whole mass of gas-containing gel or liquid, which comprises, in combination, a filler line, means for connecting said filler line in fluidtight relationship to said container, a gas vent in the top of the container adapted to release air from the container as it is filled, a check valve in said filler line to prevent reverse flow of the gas-containing liquid or gel from said container, said gas vent including closure means which are effectively closed by and sealed by the liquid or gel itself when said liquid or gel reaches the top of said container.
 5. Apparatus according to claim 4 wherein the gas vent element contains a small self-closing opening suitable for flow of gas but adapted to be plugged by the viscous liquid per se.
 6. Apparatus according to claim 4 which includes a fluidtight bayonet joint in said connecting means for connecting the filler line to the receptacle.
 7. Apparatus according to claim 4 which includes a foraminated gas vent element adapted to permit air but not viscous liquid to flow therethrough and additional positive closure means to prevent flow of either gas or liquid through said element.
 8. Apparatus according to claim 7 which includes a flap valve to prevent backflow of viscous liquid from container to the filler line. 